We're going to have waves of Retro like comic books. To me, Retro is only the late 70s to mid 80s since Retro is meant to represent the beginnings of a trend. Label each wave by their bit era and there ya go. Very easy to understand metric. However, none of the consoles use more than 128-bit processing, so technically the last 20 years is one wave.
Anyways, to answer the question, PS2 is retro, but only through the shallow definitions of retro equals antique (aka, more than 15 years old.)
The Weebs fleeced my vidja collection.